1. Field of the Invention
The present invention relates to electostatographic copying and printing machines of the type having electronic imaging, and more particularly to improving the quality of images such machines produce by automatically adjusting process control parameters.
2. Description of the Prior Art
In electrostatographic machines such as printers and copiers, image contrast, density, and color balance can be adjusted by changing certain process control parameters. Such process control parameters most frequently include initial charge V.sub.0, exposure E.sub.0, and developer bias voltage V.sub.bias. Other process control parameters which are less frequently used, but which are effective to control the copy contrast, density, and color balance include the concentration of toner in the developer mixture and the image transfer potential.
The existing techniques for regulation of electrostatographic machine process control parameters are either very expensive or user-unfriendly. For example, a test patch or patches may be formed and developed on non-image areas of an image transfer member. The resulting toner densities of the patches are used to control at least some of the process control parameters, but such a system is expensive to build.
Another technique involves operator-adjustable knobs for setting process control parameters. Although less expensive, this technique involves an iterative operator adjustment of several variables, and usually requires multiple test runs. Since the process control parameters are interrelated, their proper adjustment by an operator would require considerable skill and judgement on his or her part.